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A Tale of Two Cobalts

Citation

Laga, Stephanie Midori (2014) A Tale of Two Cobalts. Senior thesis (Major), California Institute of Technology. doi:10.7907/1B9V-AW18. http://resolver.caltech.edu/CaltechTHESIS:05192014-150810287

Abstract

There are important problems to overcome if solar energy or other renewable energy sources are to be used effectively on a global scale. Solar photons must not only be harvested and converted into a usable form, but they must also be efficiently stored so that energy is available for use on cloudy days and at night. In this work, both the energy conversion and energy storage problems are addressed. Specifically, two cobalt complexes were designed and their reactivity probed for applications in energy conversion and storage. The first chapter describes a cobalt complex that is the first example of a dimeric cobalt compound with two singly proton-bridged cobaloxime units linked by a central BO4--bridge. Using electrochemical methods, the redox properties of the dimer were evaluated and it was found to be an electrocatalyst for proton reduction in acetonitrile.

Because hydrogen gas is difficult to handle and store, the hydrogenation of CO2 and later dehydrogenation of the liquid product, formic acid, has been proposed as a hydrogen storage system. Thus, a second complex, described in chapter two, supported by a triphosphine ligand framework was used as a catalyst precursor for this key dehydrogenation step. The studies here demonstrate the efficacy of the complex as a precatalyst for the desired reaction, with good conversion of starting formic acid to CO2 and H2. In order to better understand the properties of the triphosphine cobalt complex, a synthetic procedure for substituting electron donating groups (e.g., methoxy groups) onto the ligand was investigated, yielding a novel diphosphine cobalt(II) complex.

Item Type:Thesis (Senior thesis (Major))
Subject Keywords:solar energy, hydrogen evolution, hydrogen storage, cobalt, glyoxime, triphosphine, formic acid, dimer
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Awards:Library Friends Senior Thesis Prize Winner, 2014
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Gray, Harry B.
Thesis Committee:
  • None, None
Defense Date:30 April 2014
Funders:
Funding AgencyGrant Number
Caltech Summer Undergraduate Research FellowshipUNSPECIFIED
NSF Center for Chemical Innovation in Solar FuelsUNSPECIFIED
Chevron-PhillipsUNSPECIFIED
Record Number:CaltechTHESIS:05192014-150810287
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:05192014-150810287
DOI:10.7907/1B9V-AW18
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8244
Collection:CaltechTHESIS
Deposited By: Stephanie Laga
Deposited On:10 Jun 2014 17:53
Last Modified:11 Apr 2019 17:48

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